It is known to create visible patterns or images on glass sheets, including glass windowpanes, by means of glass and/or ceramic “inks,” i.e., mixtures of a liquid carrier and powdered glass and/or ceramic pigments. The inks are typically applied to the glass sheets at room temperature, dried, and then fired at high temperature to fuse the pigments to the surface of the glass. The ink pattern is typically applied to the glass using a traditional silkscreen process. Recently, digital direct-on-glass (i.e., ink-jet) technology has been developed for applying glass and/or ceramic ink patterns to glass sheets by means of print heads which dispense ink while moving closely over the surface of the sheet. These print heads may use thermal dispensing, piezo-electric dispensing, or continuous dispensing technologies.
Insulating glass units (also known as insulating glazing units or IGUs) and vacuum insulating glass units (also known as vacuum insulating glazing units or VIGUs) are known comprising two parallel but spaced-apart sheets, or panes, of glass attached and/or sealed to one another around their respective peripheries, often by means of a frame. The gap between the sheets defines a cavity. In IGUs, the cavity is filled with air or other gasses such as argon, krypton or xenon whereas in VIGUs, the gap is “filled” with a reduced pressure atmosphere or a vacuum. Spacers are typically disposed within the gap of IGUs and VIGUs to maintain the gap. In the case of VIGUs, spacers are particularly necessary in order to support the sheets against the pressure of the outside air, which otherwise might distort or damage the glass, or cause the two panes of glass to come in contact with each other so as to produce a thermal “short circuit” (i.e., a thermally conductive path directly through the panes).